Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and a rotor. The rotor typically includes a rotatable hub having one or more rotor blades attached thereto. A pitch bearing is typically configured operably between the hub and the rotor blade to allow for rotation about a pitch axis. The rotor blades capture kinetic energy of wind using known airfoil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
Changes in atmospheric conditions, for example, wind speed, wind turbulence, wind gusts, wind direction, and density may significantly influence power produced by the generator. A power output of the generator increases with wind speed until the wind speed reaches a rated wind speed for the turbine. At and above the rated wind speed, the generator operates at a rated power. The rated power is an output power at which the generator can operate with a level of fatigue or extreme load to turbine components that is predetermined to be acceptable. At wind speeds higher than a certain speed, typically referred to as a “trip limit” or “monitor set point limit,” the wind turbine may implement a control action, such as shutting down or de-rating the wind turbine in order to protect wind turbine components from damage. A static rated power and static trip limit are typically determined during a design stage of the wind turbine and therefore are not dependent upon changing wind conditions that may be present during operation of the wind turbine, such as high wind turbulence intensity or sudden wind gusts.
Conventional systems and methods for controlling wind turbines during such transient wind conditions utilize one or more sensors positioned on the wind turbine to detect wind conditions. For example, a wind speed sensor positioned on the wind turbine will measure a wind gust at substantially the same time as the wind gust strikes the rotor blades. As such, wind turbine operation adjustments are subject to a time lag between measurement of the wind gust and the control action. As a result, the wind gust may cause rotor acceleration that will create excessive turbine loading and fatigue. In some instances, the wind gust may cause the rotor speed or power output to exceed a trip limit, before a wind turbine operation adjustment is completed, causing a wind turbine shut down.
Other systems and methods have utilized upwind measuring sensors, such as LIDAR sensors, to address the aforementioned time lag. As such, a change in wind acceleration may be measured upwind from the wind turbine, and the control action may be preemptively adjusted to compensate for the change in wind speed once the wind reaches the wind turbine. Still further control technologies estimate a wind condition experienced by the wind turbine using various algorithms. Inputs to such algorithms may change slowly causing a time lag between estimating the wind condition and implementing the control action.
Accordingly, an improved system and method for detecting a transient wind condition upwind of a wind turbine so as to reduce loads acting on the wind turbine would be desired in the art. Further, a system and method that incorporated existing hardware and software would be advantageous.